Tim is the Senior Journalist at routeONE magazine is also the title’s chief test driver, with considerable vehicle knowledge

Hybrid is here for coaches as i4H makes its debut

Alternative power has arrived in the coach sector with the Irizar i4H integral. It has a hybrid propulsion package; the dealership’s priority now is to gain in-service experience of the Cummins/Fuller driveline

In the correct application, the i4H integral can deliver 20% fuel savings

Irizar UK is the first dealership to bring a hybrid coach to the UK market, in the form of a parallel-configured, Cummins-engined i4H integral.

The demonstrator has arrived already and the next step will be in-service trials to gain real-world experience of the applications that it suits best.

A combined fleet of 30 i4H integrals and i3H integral buses on interurban work in Madrid have shown that a fuel saving of more than 20% over a comparable diesel is possible under some circumstances.

“The hybrid needs varied driving conditions to deliver its best; if it is constantly used on the motorway there will be little benefit to fuel consumption,” says Irizar UK Business Development Director Julie Hartley.

Instead, the i4H integral is tilted more towards work that involves some urban running.

The demonstrator will enter service with Travel de Courcey on a corporate contract as part of the knowledge-gathering exercise, and Irizar UK already reports interest from other parties.

“We will trial the coach with a variety of operators to get feedback on where it sits within the operational sphere,” adds Mrs Hartley. “But we believe that there is definitely a market for a hybrid. The more we see of it, the more excited we are to be the first to bring such a coach to the UK.”

Weight the same

In packaging the driveline, Irizar has maintained an unladen weight equal to that of a comparable diesel, and the hybrid package – including batteries – is contained entirely within the engine bay.

“The i4H integral has the same ‘envelope’ as a diesel, extending to luggage capacity and saloon layout,” says Mrs Hartley. Irizar UK has specified the high-floor, sunken-gangway demonstrator with 57 i6 seats, making it suited to commuter work and longer-distance duties.

Its nearside centre door includes a step-mounted wheelchair lift; a removable platform on which two seat pairs are mounted is opposite, and a wheelchair user would travel there.

The dealership will also be able to supply a mid-floor i4H where the seat plinth is lowered to sit flush with the aisle. That gives rise to the possibility of 70 seats, and Mrs Hartley does not rule out a lower-floored example if demand dictates.

“Anything that we can do with a diesel i4 integral, we can do with the i4H,” she says. The model can be PSVAR-certified if required, making it suitable for use on local services.

i4H integral demonstrator will enter service with Travel de Courcey soon

Under the bonnet

Where the i4H differs from other Irizar integrals is under the bonnet. It is the first for the UK to have a Cummins engine, with a 6.7-litre ISB6.7 developing 300bhp coupled to a Fuller hybrid package that includes a six-speed automated gearbox and a 100bhp electric motor.

A visual comparison of the hybrid and diesel integral rear modules shows that they are completely different.

The hybrid has a large black box to the left of the engine that houses the lithium-ion batteries, and its radiator is longer; cooling fans are electrically-powered, rather than hydraulic. Irizar is also at pains to point out that the hybrid package is very simple.

While the i4H does not yet have zero-emission capability, Irizar continues to develop the hybrid driveline, including the addition of higher-powered versions. Currently, the most that the i4H can deliver is 350bhp, and not the theoretical maximum 400bhp of its engine and motor combination.

How does it work?

Optimum fuel efficiency is delivered by using a mix of diesel and electric power. From stationary the i4H uses the electric motor. The engine engages as speed rises, although it runs whenever the coach is moving even if at idle. It switches off when the handbrake is applied.

At higher road speeds, power from both sources is ‘blended’, and when slowing or descending hills the engine is disengaged to permit maximum regeneration.

“The i4H is designed without any fundamental changes to the existing model and that is one of its principal attractions,” says Mrs Hartley.

“It was a joint decision by Irizar and ourselves to make the UK the second country to get the hybrid coach, which is an indication of the potential that we see for it here.” That potential does not end there, and Irizar UK has confirmed that it will also be importing the i3H hybrid bus.